1. Field of Invention
A novel activated ascorbic acid in the form of a "complex", which has important antioxidant properties in water-insoluble substrates such as fats, oils, flavorings, and carotenoid preparations.
2. Background of the Invention and Prior Art
Oxidation of fats, oils, flavorings, and carotenoids is well known to degrade these substances, reducing the biological activity of vitamins or provitamins they may contain, diminishing their color stability, creating undesirable flavors and aromas, and also creating various oxidized forms thereof, especially of fats, which are considered to be injurious to health.
Inhibition of this oxidation process is normally accomplished commercially be the addition of synthetic antioxidants. These are adapted to the particular substrate, e.g., fat, oil, carotenoid, or flavoring, by the user prior to its incorporation into food. A primary reason for not incorporating the antioxidant earlier is the requirement that the antioxidant be selected for the particular substrate--food to be stabilized. Specific antioxidants are not generally adapted to be incorporated into all foods.
Synthetic antioxidants have played, and continue to play, the most important role in substrate stabilization. Among these are propyl gallate, butylated hydroxyanisole, butylated hydroxy toluene, tertiary butylated hydroxy quinone (which is not permitted for use in the EEC or Japan), and fatty acid esters of ascorbic acid, such as ascorbyl palmitate. More recently, the public distrust of the use of synthetic substances in foods has encouraged the food industry to substitute natural antioxidants for the synthetic ones. Of most importance in this category are rosemary extracts and tocopherols.
The oxidative process begins immediately upon completion of the refining of the substrate, and it is most efficacious to introduce the antioxidant immediately upon completion of refining. This prevents the formation of oxidation promoters, which are the first step in the oxidative process. Addition of antioxidants hours or days after refining is much less effective, since the initiators propagate themselves, and the antioxidant dosage must be much greater to counteract them. Refiners and users of the existing fat-soluble antioxidants, whether natural or synthetic, cannot take advantage of the added protection which their immediate addition would afford, since the synthetics are only used in specific food applications, and the naturals may have flavor or other effects which are not universally acceptable.
Ascorbic acid, which is water-soluble and fat-insoluble, is considered to be an antioxidant in some aqueous systems, although it has also been reported to be a pro-oxidant to carotenoids in orange juice. In prepared meats it is widely used to preserve the color, where it acts as a reducing agent which converts nitrates and nitrites to nitrous oxide, which then reacts with heme pigments to form stable red colors. It is not an antioxidant in that application. It is added as a powder and becomes dissolved in the aqueous phase of the food, or as a solution in water. It has not been used in the stabilization of essentially water-insoluble substances, such as fats, oils, carotenoids, and terpene flavorings, in which applications the art has considered it ineffective. This is in accord with the teaching of the present specification.
Since the prior art considers ascorbic acid to be ineffective as an antioxidant in hydrophobic substrates, it uses synthetic fatty acid ester derivatives, which are fat soluble. These esters are exceptionally costly and do not fall within the narrow definition of natural. Surprisingly, they are not as effective on a weight for weight basis as the activated ascorbic acid of this invention.
More recently, a ternary mixture of ascorbic acid, lecithin (an ionic phospholipid), and tocopherols has been shown to possess greater antioxidant properties than identical mixtures of ascorbyl palmitate, lecithin, and tocopherols. Mixtures of lecithin and ascorbic acid were not shown to be effective, but that development was dependent upon tocopherols being present to form a ternary mixture. The presence of lecithin is objectionable according to my findings, and the presence of tocopherols may be advantageous, but is strictly optional according to my invention.
In addition to being effective as an antioxidant for fats, oils, flavorings, carotenoids, and the like, the activated ascorbic acid of this invention represents a great improvement over the prior art in the stabilization of carotenoids and especially carotenoid colors. The prior art uses synthetic antioxidants, such as ethoxyguin, or encapsulation in a gelatin matrix of a carotenoid dissolved in a solvent (with subsequent removal of the solvent), to protect the carotenoid from fading. This invention achieves the same results without the use of objectionable solvents, as well as protecting against failure in the encapsulation process.